Have you ever encountered a very [special] fault? ? ? - appliance repair - Huaqiang Electronic Network

Probe current voltage pin 290*3600 needle head diameter is 3.5mm can be too large

MOS power IC full range

Photocoupler

Today, I received a 50-inch [SAMSUNG] (PDP) TV set, model: PN50B450B1D power-on test machine, standby red light flashed, and accompanied by the relay dripping... 嘀㗳... humming sound, press The standby button and the remote control button also showed no signs of reaction. For this reason, I removed the back cover and prepared for troubleshooting, and made a set of plans and steps to decide the power board as the entry point for finding faults. First, I will put the power board. All the plugs are unplugged (including the screen line), then the VS output is connected with a 220V100W bulb as a dummy load, and then a 2K resistor is connected to the STBY at the VS-ON end, and the PS-ON is shorted to the ground. Let the power board start working independently to verify the normality of the power board. At this time, I quickly measured the voltages of 5·3V, 15V, VS207V and VA54V, and the load bulbs also illuminate normally. OK! The power board is all normal. Then, the power board is restarted and reconnected all the plugs. When connected to the Y board and the Y buffer board, only the relay of the power board is heard and the relay is protected. Then the relay rings again. Two sounds. Obviously, the fault is in the Y buffer board. Immediately after the buffer board is smashed, the Z board is plugged in, the power board is protected, and the Z board is removed immediately. Two STK1820 and two other FGPF50N33 are found after inspection. The pipe was scrapped, that is, another fault occurred in the Z board. The work in this investigation was basically completed. The next step was the handling and elimination of the fault. At this point, I was relieved and drank a cup of tea. Then, I got the relevant accessories from the warehouse and installed the test machines one by one, haha! The image appeared, and I was very proud to sit on the sofa and enjoy the show while drinking tea. It’s too early to be happy! The image seems a bit strange, is it a dazzling? I quickly brushed my eyes, and it turned out that the image was a little bit of a flower screen (grimace), and now I was dizzy. When my mood was somewhat lost, my mind kept thinking, the Y board had a problem? Do not rule out! Is there a problem with the Z board? Do not rule out! ! What is the reaction to the fine tuning of the Y and Z boards under my heart? As a result, the image quality did not improve. Therefore, I removed the Z board again and checked it. By the way, I plugged in the Y board, haha! Strange, how can the image appear when the Z board is missing? And the picture quality is the same as the original, this time made me full of dew, I can't figure it out for a while, ah, I understand, this fault was originally caused by the Z board! After checking that the Z plate had a RJH3044 pipe that was replaced, I found a piece of the same type of dismantled pipe welded to the test machine, haha! ! OK! OK! Finally OK! The HD image finally appeared! I am so excited! In the past, I have also repaired such a machine. Unfortunately, at this time, Jiawei has not been discovered by me, I am sorry! I missed a lot of opportunities to share and discuss with the altar friends. In this maintenance case, don't be misled by the appearance of some faults, because a plasma machine can play images and sounds without the Z board. This Samsung plasma "High-tech", what do you mean? According to the opinion of the fools, the practicality is not feasible at present. If the answer is no, it needs to be tested in the future practice! Masters, what happened to you during your maintenance career? Fools sincerely hope that the masters will exchange and discuss together. Thank you! Thank you all!